There are existing Liquid Natural Gas (LNG) Carriers in the market serving as LNG transportation vessels, and some of them are approaching the end of the charterer period, and/or available for life-extension program for continuous services as the LNG Carriers or other purposes. LNG Carriers are usually well-maintained vessel and in particularly the LNG storage tanks are still at good conditions. These existing carriers are mainly of 4 types of containment systems:                1) IGC Independent Tank Type-B MOSS System (Spherical Dome)        2) IGC Independent Tank Type-B SPB System (IHI)        3) Membrane Type LNG Containment System (GTT)        4) IGC Independent Tank Type-C Pressurized System        
Similar to FPSO conversion from crude oil tanker, there are markets for these existing LNG carriers to be converted into offshore or near-shore oil and gas processing facilities, such as LNG export or import facilities, as they term as FLNG (Floating Liquefied Natural Gas) units and FSRU (Floating Storage & Regasification Unit).
However, some of these existing LNG carriers have their limitation to be redeployed for these purposes and thus there exists a need for technical solutions. Some of these limitations are related to lacking of available space and/or storage capacities on existing LNG carrier to better serve its new purposes. For example, MOSS Type LNG carriers has very limited deck space available for more gas processing facilities, and this imposes limitation for its suitability to be converted into FLNG; some of the earlier generation of LNG carriers are also lesser in LNG storage capacities, e.g. below 130,000 m3 which are less ideal as FSRU receiving terminal.
As for existing LNG carriers, these vessels have been optimized to have maximum storage and transportation efficiency. Existing LNG carriers have fully utilized the available space of the vessel for the LNG storage tanks, hence there is no enough space to further increase the storage capacity on a given vessel. In addition, such vessels do not have facilities required to process the LNG, e.g. the regasification process facility and/or liquefaction process facility, as these are conventionally carried out at the offshore or near shore terminals. These existing LNG carriers are also usually less efficient than the newer generation bigger LNG carriers, which are built with larger LNG storage capacities with higher transportation efficiencies. This also means that the older and smaller capacity yet still functional vessels are at competitive disadvantage even if they continue to function for LNG transportation as compare with the newer generation of LNG carriers. These existing LNG carriers may be converted to be used as FLNG or FSRU, however in some cases, limited due to storage space constraints.